1. Field of the Invention
The present invention relates to an engine oil pump, especially an engine oil pump that has simplified transmission mechanism for adjusting an output volume flow rate of engine oil.
2. Description of the Prior Art(s)
An engine oil pump is used for pressurizing and circulating engine oil. The engine oil pump provides the engine oil to a cylinder of an internal combustion engine for the purpose of lubrication, so as to allow pistons to slide smoothly.
With reference to FIG. 7, a conventional engine oil pump comprises a main seat 61, a regulating valve 62, an inner rotor 63, an outer rotor 64, and an eccentric wheel 65. The main seat 61 has a first oil chamber 611, a second oil chamber 612, a pressurizing chamber 613, an oil return channel 614, and an oil regulating chamber 615. The pressurizing chamber 613 is formed between the first oil chamber 611 and the second oil chamber 612. The oil regulating chamber 615 communicates between the second oil chamber 612 and the oil return channel 614. The regulating valve 62 is mounted in the oil regulating chamber 615. The inner rotor 63 and the outer rotor 64 engage with each other and are mounted in the pressurizing chamber 613. The eccentric wheel 65 surrounds the outer rotor 64 and is connected to the regulating valve 62 via a transmission assembly 66.
When output oil pressure of the conventional oil engine pump is raised, the engine oil with raised output oil pressure pushes the regulating valve 62 to slide. Then the regulating valve 62 drives the eccentric wheel 65 to rotate by an angle via the transmission assembly 66. Thus, quantity of the engine oil that is pressurized by the inner rotor 63 and the outer rotor 64 and is delivered to the second oil chamber 612 is reduced. Moreover, some of the engine oil in the second oil chamber 612 of the main seat 61 flows into the oil regulating chamber 615, so the output oil pressure can be lowered. The engine oil in the oil regulating chamber 615 may further flow back to the first oil chamber 611 via the oil return channel 614 to lower down the output oil pressure automatically. Therefore, the conventional engine oil pump that has the transmission assembly 66, the eccentric wheel 65, and the gear type inner and outer rotors 63, 64 mounted in the main seat 61, and the regulating valve 62 mounted in the oil regulating chamber 615 of the main seat 61 can well control flowing of the engine oil.
In the conventional engine oil pump, the transmission assembly 66 includes multiple gears engaging with each other, so as to drive the eccentric wheel 65 to rotate and to regulate and to circulate the engine oil. However, the conventional engine oil pump with the multiple gears needs too many components for driving related mechanisms. Therefore, the conventional engine oil pump has high manufacturing cost and high assembling complexity. Furthermore, since the gears transmit movements indirectly, the transmission assembly 66 of the conventional engine oil pump is inefficient.
To overcome the shortcomings, the present invention provides a variable flow engine oil pump to mitigate or obviate the aforementioned problems.